Special Issue "Selected Papers from the XII International Conference on Computational Heat, Mass and Momentum Transfer (ICCHMT2019)"

A special issue of Entropy (ISSN 1099-4300). This special issue belongs to the section "Thermodynamics".

Deadline for manuscript submissions: closed (30 November 2019).

Special Issue Editors

Prof. Dr. Inż Jan Taler
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Guest Editor
Politechnika Krakowska, Institute of Thermal Power Engineering, 31-864 Krakow, Poland
Interests: power engineering; thermodynamics; heat transfer; inverse heat transfer problems; steam boiler dynamics; thermal stresses
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Prof. Dr. Abdulmajeed A. Mohamad
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Guest Editor
Department of Mechanical and Manufacturing Engineering, University of Calgary, T2N 1N4 Calgary, AB, Canada
Interests: complex transport phenomena; fluid saturating porous medium; energy systems; double diffusion systems; micro-gravity; nanofluids; microfluidics
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Prof. Dr. Andrea Vallati
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Guest Editor
Department of Astronautics, Electrical, and Energetics Engineering DIAEE; Sapienza University of 00185 Rome, Italy
Interests: thermodynamics; heat transfer; numerical methods
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Prof. Dr. Roberto de Lieto Vollaro
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Guest Editor
Department of Engineering, Università Degli Studi Roma Tre, 00146 Roma, Italy
Interests: energy engineering; energy systems; heat transfer
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Dr. Gabriele Battista
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Guest Editor
Department of Engineering, Università Degli Studi Roma Tre, 00146 Roma, Italy
Interests: computational fluid dynamics; heat transfer; energy; efficiency; environmental impact

Special Issue Information

Dear Colleagues,

ICCHMT is an international conference series that is widely recognized and respected in the international scientific community. ICCHMT was founded by Professor Abdulmajeed A. Mohamad from the University of Calgary, and for nearly 20 years, it has taken place in different parts of the world—Magusa, Cyprus (1999); Rio de Janeiro, Brazil (2001); Banff, Canada (2003); Paris, France (2005); Canmore, Canada (2007); Guangzhou, China (2009); Istambul, Turkey (2011 and 2015); Cracow, Poland (2016); Seoul, South Korea (2017); and Cracow, Poland (2018). In 2019, the conference will be held in Rome (Italy). The conference topics dedicated to energy topics are as follows:

  • Heat exchangers/heat pipes;
  • Fluid machinery;
  • Internal flow and heat transfer;
  • Micro/nano heat and mass transfer;
  • Mixing devices and phenomena;
  • Multi-phase flows;
  • Reactive flows and combustion;
  • Steam and gas turbines;
  • Technology for renewable energy sources;
  • Thermal flow visualization;
  • Thermal fluid machinery;
  • Transport phenomena in porous media;
  • Waste management and waste disposal.

Therefore, manuscripts within these research areas are most welcome

Prof. Dr. Inż Jan Taler
Prof. Dr. Abdulmajeed A. Mohamad
Prof. Dr. Andrea Vallati
Prof. Dr. Roberto de Lieto Vollaro
Dr. Gabriele Battista
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All papers will be peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Entropy is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 1600 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Published Papers (6 papers)

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Research

Open AccessArticle
Effect of Prandtl Number on Mixed Convective Heat Transfer from a Porous Cylinder in the Steady Flow Regime
Entropy 2020, 22(2), 184; https://doi.org/10.3390/e22020184 - 06 Feb 2020
Cited by 1
Abstract
The effect of the Prandtl number (Pr) on the flow and heat transfer from a porous circular cylinder with internal heat generation in the mixed convection regime is numerically investigated. The steady flow regime is considered over the ranges of the [...] Read more.
The effect of the Prandtl number (Pr) on the flow and heat transfer from a porous circular cylinder with internal heat generation in the mixed convection regime is numerically investigated. The steady flow regime is considered over the ranges of the Reynolds number (Re), Darcy number (Da), and Richardson number (Ri), varying from 5 to 40, 10−6 to 10−2, and 0 to 2, respectively. The wake structure, the temperature distribution, and the heat transfer rate are discussed. Besides precipitating the growth of the recirculating wake, the Prandtl number is found to have a significant impact on the thermal characteristics. The concave isotherms, resembling a saddle-shaped structure, occur behind the cylinder at larger Pr, resulting in swells of the isotherms pairing off at the lateral sides. These swells are found to have a negative effect on heat transfer owing to a relatively smaller temperature gradient there. Then, the heat transfer rate in terms of the local Nusselt number (Nu) and enhancement ratio (Er) is calculated, which is closely related to Pr, Re, Da, and Ri. The local minimum heat transfer rate along the cylinder surface is found at the position where the swells of the isotherms form. Full article
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Open AccessArticle
On Heat Transfer Performance of Cooling Systems Using Nanofluid for Electric Motor Applications
Entropy 2020, 22(1), 99; https://doi.org/10.3390/e22010099 - 14 Jan 2020
Abstract
This paper studies the fluid flow and heat transfer characteristics of nanofluids as advance coolants for the cooling system of electric motors. Investigations are carried out using numerical analysis for a cooling system with spiral channels. To solve the governing equations, computational fluid [...] Read more.
This paper studies the fluid flow and heat transfer characteristics of nanofluids as advance coolants for the cooling system of electric motors. Investigations are carried out using numerical analysis for a cooling system with spiral channels. To solve the governing equations, computational fluid dynamics and 3D fluid motion analysis are used. The base fluid is water with a laminar flow. The fluid Reynolds number and turn-number of spiral channels are evaluation parameters. The effect of nanoparticles volume fraction in the base fluid on the heat transfer performance of the cooling system is studied. Increasing the volume fraction of nanoparticles leads to improving the heat transfer performance of the cooling system. On the other hand, a high-volume fraction of the nanofluid increases the pressure drop of the coolant fluid and increases the required pumping power. This paper aims at finding a trade-off between effective parameters by studying both fluid flow and heat transfer characteristics of the nanofluid. Full article
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Open AccessArticle
Numerical Study on the Characteristics of Boger Type Viscoelastic Fluid Flow in a Micro Cross-Slot under Sinusoidal Stimulation
Entropy 2020, 22(1), 64; https://doi.org/10.3390/e22010064 - 03 Jan 2020
Abstract
The cross-slot geometry plays an important role in the study of nonlinear effects of viscoelastic fluids. The flow of viscoelastic fluid in a micro cross-slot with a high channel aspect ratio (AR, the ratio of channel depth to width) can be [...] Read more.
The cross-slot geometry plays an important role in the study of nonlinear effects of viscoelastic fluids. The flow of viscoelastic fluid in a micro cross-slot with a high channel aspect ratio (AR, the ratio of channel depth to width) can be divided into three types, which are symmetric flow, steady-state asymmetric flow and time-dependent flow under the inlet condition with a constant velocity. However, the flow pattern of a viscoelastic fluid in the cross-slot when a stimulation is applied at inlets has been rarely reported. In this paper, the response of cross-slot flow under an external sinusoidal stimulation is studied by numerical simulations of a two-dimensional model representing the geometry with a maximum limit of AR. For the cases under constant inlet velocity conditions, three different flow patterns occur successively with the increase of Weissenberg number (Wi). For the cases under sinusoidal varying inlet velocity conditions, when the stimulation frequency is far away from the natural frequency of a viscoelastic fluid, the frequency spectrum of velocity fluctuation field shows the characteristics of a fundamental frequency and several harmonics. However, the harmonic frequency disappears when the stimulation frequency is close to the natural frequency of the viscoelastic fluid. Besides, the flow pattern shows spatial symmetry and changes with time. In conclusion, the external stimulation has an effect on the flow pattern of viscoelastic fluid in the 2D micro cross-slot channel, and a resonance occurs when the stimulation frequency is close to the natural frequency of the fluid. Full article
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Open AccessArticle
Research on a Simplified Model of an Aluminum Vapor Chamber in a Heat Dissipation System
Entropy 2020, 22(1), 35; https://doi.org/10.3390/e22010035 - 25 Dec 2019
Abstract
With the rapid increase of power densities of electronic components, the traditional heat dissipation method of air forced convection has reached a heat transfer limit. As efficient phase change heat exchangers, vapor chambers have become an important guarantee for the development of high-power [...] Read more.
With the rapid increase of power densities of electronic components, the traditional heat dissipation method of air forced convection has reached a heat transfer limit. As efficient phase change heat exchangers, vapor chambers have become an important guarantee for the development of high-power electronic components. Aluminum vapor chambers have become the future development trend because they are more lightweight and less expensive. In order to study the suitable simplified model of the aluminum vapor chamber in the radiating system, the testing system is established to test the thermal characteristics of the vapor chamber. First, six simplified models of the vapor chamber are proposed. Then, the thermal characteristics of the simplified models are simulated by STAR CCM+ software. Next, the error of the thermal resistance of the simplified model and the real vapor chamber is analyzed. Finally, a most suitable simplified model is obtained in the cooling system. Full article
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Open AccessArticle
Analysis of the Influence of the Conduction Sub-Model Formulation on the Modeling of Laser-Induced Incandescence of Diesel Soot Aggregates
Entropy 2020, 22(1), 21; https://doi.org/10.3390/e22010021 - 23 Dec 2019
Abstract
Laser-induced incandescence (LII) is a powerful diagnostic technique allowing quantifying soot emissions in flames and at the exhaust of combustion systems. It can be advantageously coupled with modeling approaches to infer information on the physical properties of combustion-generated particles (including their size), which [...] Read more.
Laser-induced incandescence (LII) is a powerful diagnostic technique allowing quantifying soot emissions in flames and at the exhaust of combustion systems. It can be advantageously coupled with modeling approaches to infer information on the physical properties of combustion-generated particles (including their size), which implies formulating and solving balance equations accounting for laser-excited soot heating and cooling processes. Properly estimating soot diameter by time-resolved LII (TiRe-LII), nevertheless, requires correctly evaluating the thermal accommodation coefficient α T driving the energy transferred by heat conduction between soot aggregates and their surroundings. To analyze such an aspect, an extensive set of LII signals has been acquired in a Diesel spray flame before being simulated using a refined model built upon expressions accounting for soot heating by absorption, annealing, and oxidation as well as cooling by radiation, sublimation, conduction, and thermionic emission. Within this framework, different conduction sub-models have been tested while a corrective factor allowing the particle aggregate properties to be taken into account has also been considered to simulate the so-called shielding effect. Using a fitting procedure coupling design of experiments and a genetic algorithm-based solver, the implemented model has been parameterized so as to obtain simulated data merging on a single curve with experimentally monitored ones. Eventually, values of the thermal accommodation coefficient have been estimated with each tested conduction sub-model while the influence of the aggregate size on the so-inferred α T has been analyzed. Full article
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Open AccessArticle
Uncertainty Quantification of Film Cooling Performance of an Industrial Gas Turbine Vane
Entropy 2020, 22(1), 16; https://doi.org/10.3390/e22010016 - 22 Dec 2019
Cited by 1
Abstract
Computational Fluid Dynamics (CFD) results are often presented in a deterministic way despite the uncertainties related to boundary conditions, numerical modelling, and discretization error. Uncertainty quantification is the field studying how these phenomena affect the numerical result. With these methods, the results obtained [...] Read more.
Computational Fluid Dynamics (CFD) results are often presented in a deterministic way despite the uncertainties related to boundary conditions, numerical modelling, and discretization error. Uncertainty quantification is the field studying how these phenomena affect the numerical result. With these methods, the results obtained are directly comparable with the experimental ones, for which the uncertainty related to the measurement is always shown. This work presents an uncertainty quantification approach applied to CFD: the test case consists of an industrial prismatic gas turbine vane with standard film cooling shaped holes system on the suction side only. The vane was subject of a previous experimental test campaign which had the objective to evaluate the film cooling effectiveness through pressure-sensitive paint technique. CFD analyses are conducted coherently with the experiments: the analogy between heat and mass transfer is adopted to draw out the adiabatic film effectiveness, solving an additional transport equation to track the concentration of CO2 used as a coolant fluid. Both steady and unsteady simulations are carried out: the first one using a RANS approach with k-ω SST turbulence model the latter using a hybrid LES-RANS approach. Regarding uncertainty quantification, three geometrical input parameters are chosen: the hole dimension, the streamwise inclination angle of the holes, and the inlet fillet radius of the holes. Polynomial-chaos approach in conjunction with the probabilistic collocation method is used for the analysis: a first-order polynomial approximation was adopted which required eight evaluations only. RANS approach is used for the uncertainty quantification analysis in order to reduce the computational cost. Results show the confidence interval for the analysis as well as the probabilistic output. Moreover, a sensitivity analysis through Sobol’s indices was carried out which prove how these input parameters contribute to the film cooling effectiveness, in particular, when dealing with the additive manufacturing process. Full article
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